ELEMENTS of SCIENCE
(Meldrum - Scotland)

Eratosthenes

In 205 B.C., the Greek astronomer Eratosthenes, at the time Director of the Great Library of Alexandria in Egypt, proposed a purely geometrical method to measure the length of the Earth’s meridian (circle passing through the poles). He started by using the observation of shadows made at two different places, Alexandria and Syene (now Aswan) distanced approximately 800 km apart (distance estimated in relation to the time taken by a caravan of camels to connect the two towns !) at the time of the Summer solstice and at noon local solar time.

For this workshop, Pr Deepak Sharma, was our special guest. He organized a measurement with India.

India (Delhi)

RK Govt Sarvodaya Bal Vidyalaya,
Madanpur Khadar,
New Delhi-110076

Latitude = 28.529 or 28 deg 32’
Longitude= 77.291 or 77 deg 17’

Experiment No.1-
Object 1.00 metre and shadow 0.915 metre .
Its calculated angle (Theta) = 42°30’ = 42.5°


India (Meerut)

Meerut, India, NAS Inter College
latitude : 29°00’N
longitude 77°42’E
Gnomon : 57.1 cm
Shadow : 45°
mesures

time shadow
11.00 69.5
11.05 68.2
11.10 67.5
11.15 66.6
11.20 65.5
11.25 64.4
11.30 63.2
11.35 62.1
11.40 61.2
11.45 60.1
11.50 59.2
11.55 58.3
12.00 57.4
12.05 58.6
12.10 59.6
12.15 60.3
12.20 61.4
12.25 62.5
12.30 63.4
12.35 64.5
12.40 65.2
12.45 66.5
12.50 67.6
12.55 68.4
01.00 69.6

.

France (Lafrançaise)

with other european students
Slovenia (Medvode)
Marina di Carrara (Italy)
Valladolid (Spain)
Sibiu (Romania)
Revuca (Slovakia)
Meldrum (Scotland)

latitude 44°08’N = 44.13°
Solar noon : 12:10 UTC
Gnomon : 100cm
Shadow : 160 cm
Angle : 58°

Calculation

New Delhi
Latitude : 28.53°
angle : 42.5°
Lafrançaise
Latitude : 44.13°
angle : 58°

Distance Delhi-Lafrançaise : (44.13-28.53)x111=1732km
Difference between anles : 58-42.5=15.5°
Circumference of the earth : 1732x360/15.5 = 40227km


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